If you know the risks, you have to go into your settings and install unknown apps. Go into your biometrics and security, then scroll down you will see it.
Save them on a SD card using a Apk backup app. Try the on an old device with a anti-virus program for weeding out the bad ones. If no problems just pop the SD card in, tap on the app and a menu will come up asking you if you want to change your settings. I do it all the time with no problems. If you need to update the apps GPS and SG will update them. I use GPS, Amazon and SG for apps. Plus a few others.